Abstract: 【Objective】The cultivation pattern in the Huang-Huai-Hai Plain is double cropping system of winter wheat-summer maize. The key reason for the influence on root development and yield is the decrease of nutrient content and the tillage layer is becoming shallow which are caused by long-term no-tillage or rotary tillage is practiced in growing winter wheat and no-tillage is practiced in growing maize. It has a significant impact on root development and yield of crops. This study is to investigate the effects of different tillages on root characteristics and grain yield of summer maize in double cropping system in Huang-Huai-Hai Plain. 【Method】 Zhengdan958 (ZD958) was used as experimental materials. The field study consisted of tillage treatments before sowing winter wheat and summer maize: rotary tillage before winter wheat sowing and no-tillage before maize sowing (RN), tillage before wheat sowing and no-tillage before maize sowing (MN), and tillage before wheat sowing and rotary tillage before maize sowing (MR) were performed to explore the effects of tillage before winter wheat on root dry matter and root/shoot, root length and area, brace root quality, quantity of bleeding sap in stalk and grain yield. 【Result】The root dry weight, root/shoot ratio, root length, root surface area, root volume, brace root layer number, brace root article number and the brace root dry weight in 0-30 cm of MR and MN increased by 59.1%, 37.5%, 22.8%, 41.1%, 59.2%, 5.9%, 21.0%, 50.8%, and 68.5%, 50.0%, 16.7%, 33.7%, 44.0%, 3.9%, 20.1%, 57.6%, respectively. root TTC reducing capacity, TTC reducing quantity, root actively absorbing area, total root absorbing area and quantity of bleeding sap in 0-30 cm of MR and MN increased by 82.6%, 91.9%, 33.9%, 34.5%, 24.0%, and 109.9%, 108.5%, 83.8%, 65.1%, 14.7%, respectively. Compared to RN, actual ears, the spike grain number, 1000-kernel weight in MR and MN treatments were increased by 8.5%, 11.7%, 4.9% and 3.9%, 8.5%, 4.2%, respectively, and MR and MN treatments, respectively, increased yield by 29.5% and 23.7%. Ploughing before wheat seeding significantly improved the summer maize root quantity and quality characteristics, thus improved yield. Compared with MR, MN treatment significantly increased the total absorption area and active absorption area of the roots which increased by 22.8% and 37.21%, respectively. However, the root length, root surface area, root volume, root number, reductive amount and reductive intensity of TTC by root were not significantly different from those of MR. Compared with MN, the effective panicle number of MR increased by 4.7% but the spike grain number and 1000-kernel weight of two treatments showed no different, yield did not reach significant difference levels.【Conclusion】Compared to RN, MN and MR could significantly improve root properties and yield. The root characteristics and yield of MN and MR did not show significant difference, which indicated that the early wheat sowing was the main effect of winter wheat sowing on summer maize yield and root characteristics. In comprehensive comparison of three different farming methods, it was concluded that MN is the most suitable summer maize production farming method in Huang-Huai-Hai Plain.

Key words: summer maize, double cropping of winter wheat and summer maize, tillage method, root characteristics, grain yield